'72 C10 driveshaft, yoke, and universal.
 

I have a '72 Cheyenne Super with BB, 400 trans, 12 bolt rear that the PO took apart and I'm slowly putting back together. Put the rear drive shaft in. There's no tabs in the yoke for the universal caps to go against. Matter of fact the universal is slightly wider than the yoke ears. It fits in the U, and seats all the way in. I haven't gotten to running it down the road yet, so I don't know about vibration. Did some of these trucks come out with an arrangement like I described?

Re: '72 C10 driveshaft, yoke, and universal.
 

You likely need inside lock type u-joints.
Info here.
http://www.driveshaftspecialist.com/...D%20Guide.html

Re: '72 C10 driveshaft, yoke, and universal.
 

Thanks, Geezer, I'll check that out tomorrow. When I put the shaft in, it just seemed strange there were no tabs in the yoke, but the website you recommended had a yoe on there like that. Thank you sir!

Re: '72 C10 driveshaft, yoke, and universal.
 

They’re also known as internal clip u-joints.
You might run into a parts guy who calls them that.